A recent meta-analysis by Shaffer, Half and Bilt (1997) concluded that pathological gambling is developing into a serious public health problem. Although the rise in gambling problems has stimulated treatment outcome research, there is a shortage of systematic and controlled treatment research. Substantial progress has not been made in understanding how to treat pathological gambling. Of particular concern are the high dropout rates from treatment. To address gamblers' motivational ambivalence, we have developed and propose to test the effectiveness of a Cognitive-Motivational Behavior Therapy. The treatment is designed first, to enhance gamblers' readiness for change. Once patients are committed to treatment, the therapy then addresses specific cognitive biases regarding the notion of randomness that are assumed to lie at the heart of pathological gambling (Sylvain, Ladouceur & Boisvert. 1997). Behavioral components (problem solving. assertiveness) will also be used to enhance coping skills. Thus, by combining aspects of motivational interviewing with cognitive behavior therapy, we anticipate that this study will increase our conceptual understanding of the disorder and render empirical evidence on how to improve its treatment. We will conduct a controlled pilot study of 40 individuals who meet DSM-IV criteria for pathological gambling. As part of the study, we will conduct a detailed assessment of these patients. We will then randomly assign 20 pathological gamblers each to either the experimental treatment or to a Gamblers Anonymous control condition. Given the reported high dropout rate from Gamblers Anonymous, this condition will be the functional equivalent of a no-treatment control group without its ethical liabilities and practical limitations. Patients will be assessed prior to and after treatment and at 3- and 6-month follow-up. Measures will consist of gambling-specific interviews and questionnaires. Comorbid Axis I and Axis II psychopathology will be assessed. A challenge paradigm will be used to assess reactivity to gambling cues before and after treatment. Findings from this study are expected to inform future research on the treatment of pathological gambling.